Comparision of Mutant Selection Window Hypothesis with Traditional

Comparision of Mutant Selection Window Hypothesis with Traditional Pharmacodynamics

Serum drug concentration Pharmacodynamic Correlates with Cure Time above MIC AUC above MIC Cmax/MIC Cmax MIC Time post-administration

Serum or tissue drug concentration Dosing Strategies and Mutant Enrichment >MPC Cmax/MIC and AUC/MIC MPC Mutant Selection Window Time post-administration MIC

Comparison of MPC Approach and Traditional Pharmacodynamics MPC • • Designed to block resistance Indexed to mutant growth Conceptual threshold Clinical correlates unknown Traditional PD • • Designed to cure patients Indexed to susceptible cell growth Empirical threshold Based on clinical data

Applications to Streptococcus neumoniae

Fluoroquinolone Structure O O F OH N O N HN O F OH N N O CH 3 H 3 C ciprofloxacin levofloxacin O O F O OH OH H N N O N HN O F H H 3 C Moxifloxacin O F Garenoxacin N

Plasma drug concentration (fold of MIC) Pharmacodynamic Comparison with S. pneumoniae levo cipro 10 MPC MIC 1 0 5 10 15 20 25 Time post-administration (hr)

10 MPC (fold of MIC) Plasma drug concentration Two Situations Producing Concentrations Inside the Window cipro with S. aureus MIC 1 0. 1 levo with S. pneumoniae 0 5 10 15 20 25 Time post-administration (hr)

Levofloxacin resistance among clinical isolates of S. pneumoniae Geographic region Dates of sample Number of isolates tested % resistant USA 1994 -1995 1523 0. 3 USA 1997 -1998 1596 0. 5 USA 1999 -2000 1531 0. 7 USA 1997 -1998 2950 0. 1 USA 1998 -1999 4296 0. 6 USA 1999 -2000 9499 0. 5 USA 2000 -2001 6362 0. 8 USA/Canada 1997 -1998 3854 0. 2 -0. 3 USA/Canada 1999 1201 0. 9 Canada 1994 -1998 7224 0. 4 Canada 2000 2245 0. 9 Japan 1997 -1998 218 0. 9 China 1997 -1998 124 0. 8 Germany 1997 -1998 283 0. 4 2000 180 10 1997, 1999 138 1. 4 Hong Kong Brooklyn

Fraction of cells recovered Recovery of Fluoroquinolone-resistant S. pneumoniae Levo Moxi 1 10 -2 MIC 99 10 -4 10 -6 10 -8 10 -10 0. 1 1 [Fluoroquinolone] (μg/ml)

Plasma drug concentration (mg/ml) MPC and Fluoroquinolone Pharmacokinetics 10 9 8 7 6 5 4 3 2 1 0 Moxifloxacin MIC 90 0 MPC 90 10 20 30 40 50 10 9 8 7 6 5 4 3 2 1 0 Levofloxacin MPC 90 750 mg 500 mg MIC 90 0 10 20 30 40 50 Time post-administration (hr)

Comparison of Fluoroquinolones by MPC-based Pharmacodynamics Serum Concentration t Fluoroquinolone (hr) Moxifloxacin Gemifloxacin Gatifloxacin Levofloxacin MPC MIC Time MPC 90 (mg/ml) 2 1 4 8 Time above MPC 90 18 4 1 -2 0

Fraction of cells recovered Recovery of Fluoroquinoloneresistant S. pneumoniae Levo Moxi 1 MIC 99 10 -2 MIC 99 10 -4 10 -6 10 -8 10 -10 0. 1 1 [Fluoroquinolone] (ug/ml)

Topoisomerase Mutants Selected by Levofloxacin and Moxifloxacin Fraction of Identity of mutants* cells recovered Selected by moxi Selected by levo as mutants gyr. A gyr. B par. C par. E 3. 0 X 10 -5 4. 4 X 10 -6 1. 8 X 10 -6 2. 0 X 10 -7 none none 103 1. 3 X 10 -7 none -9 5. 6 X 10 none none none -9 1. 2 X 10 none none -10 2. 9 X 10 S 81 Y none -10 1. 6 X 10 S 81 Y none none none none none none S 79 Y none D 83 H none none S 79 Y none none * Changes in QRDR of the indicated genes none S 81 Y

Fraction of cfu recovered Effect of a par. Cr mutation on recovery of resistant mutants 1 MIC 99 par. Cr wt MIC 99 10 -2 10 -4 10 -6 10 -8 10 -10 0. 1 MPC 1 [Moxifloxacin] (mg/ml) 10 S. pneumoniae

Fluoroquinolone Challenge Adds Topoisomerase Mutations to S. pneumoniae Strain Agent Par. C Changes in QRDR Par. E Gyr. A Gyr. B D 83 G, K 137 N none E 85 K none 70 70 multiple D 83 G I 460 V Gemi K 137 N, S 79 F E 474 K 70 Moxi-1 D 83 G, K 137 N none 70 Moxi-2 D 83 G K 137 N, S 79 F none S 81 Y E 85 K, S 81 F none

Applications to Staphylococcus aureus

Mutant Selection Window and Fluoroquinolone Pharmacokinetics: S. aureus Garenoxacin (BMS 284756) Ciprofloxacin [Drug] (mg/ml) 10 7 MPC 90 30 6 cip. S 5 4 3 1 2 1 MIC 90 MPC 90 0. 03 0. 2 0 2 4 6 8 MIC 90 0 5 10 15 20 25 MPC 90 cip. R 16 14 12 10 8 6 4 2 0 MIC 90 0 Time post-administration (hr) 5 10 15 20 25

Serum or tissue drug con. MPC-based Potencywith S. aureus Compound MPC (mg/ml) Norfloxacin 22 Cmax (mg/ml) half-life (hr) 1. 45 3. 25 20 52 1. 8 Chloramphenicol 40 26 6. 5 Rifampicin 480 9. 5 2 Penicillin G 1 512 0. 9 Tobramycin Vancomycin 40 39 6. 5 Moxifloxacin 0. 6 4. 5 12 Dose above MPC Time post-administration

Compound MPC (mg/ml) MIC 99 (mg/ml) MPC/MIC 99 Norfloxacin 22 0. 85 26 Tobramycin 20 0. 27 74 40 1. 9 21 Chloramphenicol Serum or tissue drug con. Mutant Selection Window with S. aureus Rifampicin 480 0. 003 Penicillin G 1 0. 015 67 Vancomycin 40 0. 65 62 Moxifloxacin 0. 6 0. 05 160, 000 12 Narrow the window Time post-administration

Is the Mutant Selection Window Restricted to Fluoroquinolones?

Fraction of input cfu recovered Mutant Selection with Erythromycin and Penicillin M. smegmatis S. aureus 10 -1 10 -3 10 -5 10 -7 10 -9 0. 1 1 10 1000 [Erythromycin] (mg/ml) 0. 01 0. 1 1 10 1000 [Penicillin] (mg/ml)

Fraction of input CFU recovered Mutant Selection with Yeast (Canadia glabrata) clinical resistant isolate 1 10 -2 10 -4 wild-ytpe 10 -6 10 -8 0. 001 0. 1 1 10 [Miconazole] (mg/ml) 100

Why is the Selection Window Hypothesis Useful?

Number of isolates Gradual Increase of Resistance breakpoint MIC

Problems for implementing direct attack of mutants • No animal or clinical studies done • Currently requires altruism (dosing higher than needed for cure) • With S. pneumoniae time is running out (cross-resistance)

Literature Cited